Construction on a $5.7-billion bridge touted as a key link between Canada and the United States is officially underway.

Flanked by dignitaries from both sides of the border, Prime Minister Justin Trudeau said the Gordie Howe International Bridge will be built over the next five and a half years and operational by late 2024.

He made the announcement at the beginning of a jam-packed day in Windsor.

Trudeau said the 2.5-kilometre bridge spanning the Detroit River will provide a critical conduit for commerce between the two countries, an issue he said has taken on increased relevance since the successful resolution of contentious free trade negotiations earlier in the week.

"I'm confident that integrated, two-way trade between Windsor and Detroit will only increase from here, which is a great thing for local communities and the national economy," Trudeau said. "Shorter travel times, more efficient supply chains and better access to the U.S. market. The Gordie Howe International Bridge has been a long time coming."

Trudeau said the bridge was always a priority project, but has taken on added significance since Canada joined the U.S. and Mexico in signing an agreement-in-principle on a free trade deal. The pact, dubbed the U.S.-Mexico-Canada Agreement, has yet to be formally ratified.

The bridge has also survived multiple legal challenges from the private owner of the nearby Ambassador Bridge, who publicly appealed to U.S. President Donald Trump this year to revoke a presidential permit Barack Obama granted to greenlight construction.

When asked about the Ambassador Bridge, Trudeau instead said it was a great day for the Gordie Howe bridge project.

In fact, Trudeau said he has spoken with Michigan's outgoing governor, Rick Snyder, about "accelerating the timelines" for the bridge completion.

"That's very much how we're focused on getting this done as quickly as we can for the people of Detroit, of Windsor and of both of our countries," he said.

Funding for the pricey project was also a hot-button issue until the previous Conservative government agreed to have Canada finance all aspects of the project. The move essentially saw the government do an end-run around state and congressional lawmakers south of the border who were holding up construction.

On Friday, Snyder was on hand to offer a public benediction for the project.

"This is a friendship of many, many years, and what better representation than the Gordie Howe International Bridge," he said. "Gordie Howe...set the benchmark for the hockey world. This bridge will set that benchmark for the Canadian-American relationship and for the rest of the world."

Trudeau said the construction project will create an estimated 2,500 jobs and will lead to more sustained employment growth once completed.

He also touted the long-term trade benefits, saying a quarter of all trade passes through the Windsor-Detroit corridor as 7,000 commercial vehicles travel through the area daily.

Bridging North America's plan for the bridge calls for a six-lane, 2.5-kilometre cable-stayed design, which is touted as the longest cable-stayed bridge in North America with a lifespan of 125 years.

Federal officials have said the business plan for the Gordie Howe bridge is based on having a second one nearby, and plans for such a project are already in the works.

Ottawa gave its blessing to a plan to replace the nearly 90-year-old Ambassador Bridge, located just down the river from where Trudeau spoke on Friday.

But the Liberals have placed strict conditions on the Ambassador's successor, including requirements that the existing bridge be demolished. The owners of the Ambassador Bridge, the American Moroun family, have publicly stated that it could complete construction on the replacement before 2024.

Later on Friday, Trudeau met with union leaders to talk about the new trade deal. Gathered in a boardroom at a downtown hotel, Trudeau thanked them for their support through the difficult months of negotiations on the USMCA pact.

A short time later, standing amongst a group of several hundred of the workers on break at the FCA Windsor Assembly Plant, Trudeau touted the new deal, saying that workers and their families always need to be at the centre of the agreement.

Trudeau also made a brief stop at a food bank to hand out turkeys for Thanksgiving.

--With files from the Canadian Press